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The article below is an introduction to the Hansen Culture Box also described by Arroyo in Studies on Rum (1945). Nowadays the state of the art for microbiology work is the laminar flow hood ($2000-4000) and other sterile boxes, but they are often way beyond most people’s budgets. I have seen more and more new distillers getting into pure culture work and thought this idea may help a few. I have been having minor problems with aseptic technique and losing a percentage of my plates to mold.
Arroyo’s above “Hansen type” sterile transfer box differs a little bit from the article below. He has a nice angled front and then it appears a flip down portion for the hands. The thing to note is that the operating principle of the box is the film of antiseptic liquid that coats the walls (Arroyo never mentions this). Any air-born microorganims get trapped on the film and are then killed by the anti septic action. I use Star-san, but back then they used Mercury Chloride which is highly toxic and probably overkill. They likely used it because the wood would absorb it and prevent eventual mildew when the continuously moistened cabinet was not in use. HgCl was also used to pressure treat lumber for a while though it doesn’t do a good job because it is water soluble.
My improvised Hansen box is merely an off the shelf fish tank turned on its side:
Initially I improvised a door with clear vinyl sheet and magnets, but it was poorly conceived. Eventually I settled on nothing more than cling wrap:
Cling wrap is nice because you can seal it up then cut holes then re-seal it up. A 10 gallon fish tank was only $17, however I wish I bought a larger one. When I turned the tank on its side, I only had a height of roughly 12″ and I had to make a tin foil reflector for my alcohol lamp (because the glass got hot) which was easy. This cabinet is small enough I was able to add multiple ounces of sanitizer and swish it around turning the cabinet on all sides. The bazel provides enough of a lip to keep the liquid inside.
I do not yet have a lot of working experience with this idea and no doubt it can be improved. Feel free to comment if you have any thoughts, but I hope this helps anyone else having contamination troubles while attempting aseptic transfers. If I built a box like Arroyo, I would use HDPE instead of wood. If you seek to improve this, keep in mind tons of “glove boxes” and other enclosures exist, but they get pricey fast and their active principle is not antiseptic moisture to trap air-born microorganism.
There may be a lot of benefit to elaborating these techniques because the new distilling industry is about to learn that fermentation is everything. Distillates are intensely governed by garbage in / garbage out. Yeasts and bacteria are about to see a greater focus and we may start ditching the pot still rhetoric and starting discussing spirits based on their fermentation. Is it a fission yeast rum?
[After working with this a few times, I’d definitely say get a tank bigger than 10 gallons like a 20. This will give you extra ceiling height which is important. It also feels like the candle inside is also as much an operating principle as the film of antiseptic liquid. The box quickly warms up and no doubt create a flow of positive air displacement out the holes cut for your hands. At the moment I use a small alcohol lamp and a larger tank may even benefit from two if heating the air is beneficial. However I did run this box idea past an colleague from MIT. He mentioned that they liked to work not with a box but with a burner more powerful than an alcohol lamp such as a bunsen burner. He believed working in very close proximity to the flame created currents that dispelled or destroyed dust.
This same person is quite smart and answered another question. I asked if there is a way to aseptically pull small samples from a ferment, precisely dilute it to measure pH then reliably extrapolate the original pH. This would avoid contamination from sticking pH probes into multiple ferments because they are hard to clean without damaging them. I thought you needed roughly a 50 or 100 ml minimum volume to measure pH. He said you can do it with 2-5 ml by simply using a very snug and idealized sampling vessel. An ideal vessel becomes the cap the holds the pH storage solution. It typically has a fill line of a few ml and when the probe is inserted, the liquid rises to cover the junction for the pH probe and reference probe.]
THE HANSEN CULTURE BOX.
Much work in bacteriology, such as transferring cultures, inoculations of culture media, preparation of gelatine or agar-agar plates, etc., is made in an open room, with much danger in regard to infection from the atmosphere. Much of this danger may be avoided if such work as is named above is made in the Hansen Culture Box which was constructed by the famous mycologist, Emil Chr. Hansen, but yet nowhere described. The writer mentioned and described it at the Madison meeting of the American Association for the Advancement of Science, in August, 1893.
The Hansen Box is rectangular (see fig.,) with panes in top and the four sides. The bottom should be made of heavy, hard wood, such as hickory or oak, as it must not bend when moistened. In front, a sliding door (A A) is fitted tightly. This door can be placed in different positions, as the figure shows, allowing a larger or smaller opening in front. About ten minutes before being used, this box is washed carefully in and outside with a 1 p. m. sol. of corrosive sublimate (Hg Cl.,) and then closed. After a while, the newly sterilized utensils are put into the box, and arranged in a manner which experience will indicate. A small cross-bar prevents dust from slipping in at the top of the door.
When the utensils have been put in, the box should again be closed. The hands of the worker are then carefully washed, and the slide-door pushed upwards until it leaves space enough for the hands and a part of the arms to work inside. A small alcohol lamp may be kept in the box for the final disinfection of needles, covers, slides, etc. The latter utensils may be placed on a small tray which can be sterilized without any difficulty, in a flame.
When the box has been used once, everything should be taken out, and the inside cleaned with sublimate. Immediately before it is used again it must be re-washed, so that the inside always can be moist while the worker is operating. The moist walls will catch the micro-organisms that may be within.
Like much bacteriological apparatus, this box is not expensive; it can be made by a carpenter, and should be polished on the outside, while the inside is merely varnished.